[12/15] plugin: propagate errors

qemu_finish_machine_init currently can only exit QEMU if it fails.
Prepare for giving it proper error propagation, and possibly for
adding a plugin_add monitor command that calls an accelerator
method.

While at it, make all errors from plugin_load look the same.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/qemu/plugin.h |  4 ++--
 linux-user/main.c     |  4 +---
 plugins/loader.c      | 34 +++++++++++++++++-----------------
 softmmu/vl.c          |  4 +---
 4 files changed, 21 insertions(+), 25 deletions(-)

Paolo Bonzini <pbonzini@redhat.com> writes:

> qemu_finish_machine_init currently can only exit QEMU if it fails.
> Prepare for giving it proper error propagation, and possibly for
> adding a plugin_add monitor command that calls an accelerator
> method.
>
> While at it, make all errors from plugin_load look the same.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Acked-by: Alex Bennée <alex.bennee@linaro.org>

On Wed,  2 Dec 2020 03:18:51 -0500
Paolo Bonzini <pbonzini@redhat.com> wrote:

> qemu_finish_machine_init currently can only exit QEMU if it fails.
> Prepare for giving it proper error propagation, and possibly for
> adding a plugin_add monitor command that calls an accelerator
> method.
> 
> While at it, make all errors from plugin_load look the same.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  include/qemu/plugin.h |  4 ++--
>  linux-user/main.c     |  4 +---
>  plugins/loader.c      | 34 +++++++++++++++++-----------------
>  softmmu/vl.c          |  4 +---
>  4 files changed, 21 insertions(+), 25 deletions(-)
> 
> diff --git a/include/qemu/plugin.h b/include/qemu/plugin.h
> index ab790ad105..841deed79c 100644
> --- a/include/qemu/plugin.h
> +++ b/include/qemu/plugin.h
> @@ -45,7 +45,7 @@ static inline void qemu_plugin_add_opts(void)
>  }
>  
>  void qemu_plugin_opt_parse(const char *optarg, QemuPluginList *head);
> -int qemu_plugin_load_list(QemuPluginList *head);
> +int qemu_plugin_load_list(QemuPluginList *head, Error **errp);
>  
>  union qemu_plugin_cb_sig {
>      qemu_plugin_simple_cb_t          simple;
> @@ -199,7 +199,7 @@ static inline void qemu_plugin_opt_parse(const char *optarg,
>      exit(1);
>  }
>  
> -static inline int qemu_plugin_load_list(QemuPluginList *head)
> +static inline int qemu_plugin_load_list(QemuPluginList *head, Error **errp)
>  {
>      return 0;
>  }
> diff --git a/linux-user/main.c b/linux-user/main.c
> index 24d1eb73ad..750a01118f 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -671,9 +671,7 @@ int main(int argc, char **argv, char **envp)
>          exit(1);
>      }
>      trace_init_file();
> -    if (qemu_plugin_load_list(&plugins)) {
> -        exit(1);
> -    }
> +    qemu_plugin_load_list(&plugins, &error_fatal);
>  
>      /* Zero out regs */
>      memset(regs, 0, sizeof(struct target_pt_regs));
> diff --git a/plugins/loader.c b/plugins/loader.c
> index 8ac5dbc20f..5cb9794fda 100644
> --- a/plugins/loader.c
> +++ b/plugins/loader.c
> @@ -150,7 +150,7 @@ static uint64_t xorshift64star(uint64_t x)
>      return x * UINT64_C(2685821657736338717);
>  }
>  
> -static int plugin_load(struct qemu_plugin_desc *desc, const qemu_info_t *info)
> +static int plugin_load(struct qemu_plugin_desc *desc, const qemu_info_t *info, Error **errp)
>  {
>      qemu_plugin_install_func_t install;
>      struct qemu_plugin_ctx *ctx;
> @@ -163,37 +163,37 @@ static int plugin_load(struct qemu_plugin_desc *desc, const qemu_info_t *info)
>  
>      ctx->handle = g_module_open(desc->path, G_MODULE_BIND_LOCAL);
>      if (ctx->handle == NULL) {
> -        error_report("%s: %s", __func__, g_module_error());
> +        error_setg(errp, "Could not load plugin %s: %s", desc->path, g_module_error());
>          goto err_dlopen;
>      }
>  
>      if (!g_module_symbol(ctx->handle, "qemu_plugin_install", &sym)) {
> -        error_report("%s: %s", __func__, g_module_error());
> +        error_setg(errp, "Could not load plugin %s: %s", desc->path, g_module_error());
>          goto err_symbol;
>      }
>      install = (qemu_plugin_install_func_t) sym;
>      /* symbol was found; it could be NULL though */
>      if (install == NULL) {
> -        error_report("%s: %s: qemu_plugin_install is NULL",
> -                     __func__, desc->path);
> +        error_setg(errp, "Could not load plugin %s: qemu_plugin_install is NULL",
> +                   desc->path);
>          goto err_symbol;
>      }
>  
>      if (!g_module_symbol(ctx->handle, "qemu_plugin_version", &sym)) {
> -        error_report("TCG plugin %s does not declare API version %s",
> -                     desc->path, g_module_error());
> +        error_setg(errp, "Could not load plugin %s: plugin does not declare API version %s",
> +                   desc->path, g_module_error());
>          goto err_symbol;
>      } else {
>          int version = *(int *)sym;
>          if (version < QEMU_PLUGIN_MIN_VERSION) {
> -            error_report("TCG plugin %s requires API version %d, but "
> -                         "this QEMU supports only a minimum version of %d",
> -                         desc->path, version, QEMU_PLUGIN_MIN_VERSION);
> +            error_setg(errp, "Could not load plugin %s: plugin requires API version %d, but "
> +                       "this QEMU supports only a minimum version of %d",
> +                       desc->path, version, QEMU_PLUGIN_MIN_VERSION);
>              goto err_symbol;
>          } else if (version > QEMU_PLUGIN_VERSION) {
> -            error_report("TCG plugin %s requires API version %d, but "
> -                         "this QEMU supports only up to version %d",
> -                         desc->path, version, QEMU_PLUGIN_VERSION);
> +            error_setg(errp, "Could not load plugin %s: plugin requires API version %d, but "
> +                       "this QEMU supports only up to version %d",
> +                       desc->path, version, QEMU_PLUGIN_VERSION);
>              goto err_symbol;
>          }
>      }
> @@ -220,8 +220,8 @@ static int plugin_load(struct qemu_plugin_desc *desc, const qemu_info_t *info)
>      rc = install(ctx->id, info, desc->argc, desc->argv);
>      ctx->installing = false;
>      if (rc) {
> -        error_report("%s: qemu_plugin_install returned error code %d",
> -                     __func__, rc);
> +        error_setg(errp, "Could not load plugin %s: qemu_plugin_install returned error code %d",
> +                   desc->path, rc);
>          /*
>           * we cannot rely on the plugin doing its own cleanup, so
>           * call a full uninstall if the plugin did not yet call it.
> @@ -263,7 +263,7 @@ static void plugin_desc_free(struct qemu_plugin_desc *desc)
>   * Note: the descriptor of each successfully installed plugin is removed
>   * from the list given by @head.
>   */
> -int qemu_plugin_load_list(QemuPluginList *head)
> +int qemu_plugin_load_list(QemuPluginList *head, Error **errp)
>  {
>      struct qemu_plugin_desc *desc, *next;
>      g_autofree qemu_info_t *info = g_new0(qemu_info_t, 1);
> @@ -283,7 +283,7 @@ int qemu_plugin_load_list(QemuPluginList *head)
>      QTAILQ_FOREACH_SAFE(desc, head, entry, next) {
>          int err;
>  
> -        err = plugin_load(desc, info);
> +        err = plugin_load(desc, info, errp);
>          if (err) {
>              return err;
>          }
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index e5f3c42049..0f63d80472 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -2417,9 +2417,7 @@ static void qemu_init_board(void)
>      }
>  
>      /* process plugin before CPUs are created, but once -smp has been parsed */
> -    if (qemu_plugin_load_list(&plugin_list)) {
> -        exit(1);
> -    }
> +    qemu_plugin_load_list(&plugin_list, &error_fatal);
>  
>      /* From here on we enter MACHINE_PHASE_INITIALIZED.  */
>      machine_run_board_init(current_machine);